Fun With Antennas

I got back on the shortwave bands in August, putting up a 20m dipole. While 20m is fun, I’ve wanted to try out some of the other bands, too. When I was a kid, I used to work 40m a lot, especially late at night. So, I decided to put up a 40m dipole.

I’m lucky in that I have a number of trees to use as an antenna support. While there’s not quite enough space to string an 80m dipole, I guesstimated that a 40m antenna would fit quite nicely.

So, I mail-ordered a bunch of stuff from RadioWorks. The stuff was very nice quality, but I was a little miffed that some of the prices were higher than advertised. I understand that prices can change, but they really should make an effort to update the ads they run in QST and other magazines. It looks to me like they haven’t been updated for more than a year.

At any rate, I got all the parts, and in rummaging through my junk boxes came across a 1:1 balun that someone had given me. I built the dipole using that balun instead of the RadioWorks balun that I’d just purchased. The antenna wire I bought is that fancy, flexible stuff. As advertised, it was very easy to work with, and looks to be quite strong, too. I also put together a 100′ RG 59 cable.

So, Saturday afternoon I get out into the backyard and string it up. Using the Autek VA1 antenna analyzer, I adjust the length for the lowest SWR I can manage. Oddly, it doesn’t seem as though I can get it much lower than about 1.5:1, but that’s OK. It should still work. (More about this later.)

Finally, I get the thing up in the air, and hurry down to the shack to give it the smoke test. I check the SWR again with the Autek, and it looks pretty good. I connect it to my rig–an Icom IC-735–and tune around for a clear frequency. Finally, I put the power to it, and adjust the internal SWR meter.

Wow. The SWR looks even better than it did with the Autek. I send out a few Vs, and then my wife comes rushing downstairs. “”You’re coming in loud and clear,”” she says, “”over the computer speakers! AND you’re making the garage door go up and down, to boot!””

Yipes. I didn’t have this problem with the 20m dipole at all, and I thought a balun was supposed to help reduce RFI.

At this point, it was almost dinnertime, so I just pulled the plug on the rig and decided to sleep on things. It’s too bad, too, because I had wanted to make a few contacts in the CW Sweepstakes Contest. Oh well.